Reserves (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Changes in the Card Member receivable reserve for losses
Balance, January 1	$ 114	$ 94
Provisions	101	116
Other credits	13	32
Net write-offs	(105)	(124)
Other debits	(17)	(9)
Balance, September 30	$ 106	$ 109